System and method for leak detection based on prv outlet pressure monitoring

ABSTRACT

A leak detection system for a building includes a pressure regulating valve (PRV) having a PRV inlet and a PRV outlet. The PRV is operative during a flow of water through the PRV, and a PRV pressure at a lockup pressure during no water flow through the PRV. An outlet pressure sensor is fluidly coupled to the PRV outlet to measure a PRV outlet pressure. A processor is operatively coupled to the outlet pressure sensor. The processor is configured to run a pressure monitoring process to detect changes in pressure at the PRV outlet when the PRV pressure falls below the lockup pressure while remaining above a setpoint pressure to give an indicia of a fixture leak. A method to give an indicia of a fixture leak is also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of co-pending U.S.patent application Ser. No. 17/168,403, SYSTEM AND METHOD FOR LEAKDETECTION BASED ON PRV OUTLET PRESSURE MONITORING, filed Feb. 5, 2021,and co-pending U.S. provisional patent application Ser. No. 62/971,456,SYSTEM AND METHOD FOR LEAK DETECTION BASED ON PRV OUTLET PRESSUREMONITORING, filed Feb. 7, 2020, which applications are incorporatedherein by reference in their entirety.

FIELD OF THE APPLICATION

The application relates to leak detection, particularly to leakdetection at a pressure reducing valve.

BACKGROUND

Pressure regulating/reducing valves (PRV) are used to convert arelatively high pressure supply line to a relatively constant pressureoutlet. One application of a PRV is to convert a relatively highpressure municipal water supply line to a relatively constant lowerwater outlet pressure to the plumbing of a home or building. There aretwo main styles of PRVs. Direct acting regulators and pilot operatedregulators. Direct acting regulators use a spring to control the outletpressure of the PRV and are typically used in lower flow rateapplications. Pilot operated regulators use a direct acting regulator asa pilot valve to control the outlet pressure and are typically used inhigher flow rate applications, such as a large commercial building orfacility.

SUMMARY

A leak detection system for a building includes a pressure regulatingvalve (PRV) having a PRV inlet and a PRV outlet. The PRV is operativeduring a flow of water through the PRV, and a PRV pressure at a lockuppressure during no water flow through the PRV. An outlet pressure sensoris fluidly coupled to the PRV outlet to measure a PRV outlet pressure. Aprocessor is operatively coupled to the outlet pressure sensor. Theprocessor is configured to run a pressure monitoring process to detectchanges in pressure at the PRV outlet when the PRV pressure falls belowthe lockup pressure while remaining above a setpoint pressure to give anindicia of a fixture leak.

The leak detection system can further include an inlet pressure sensorfluidly coupled to the PRV inlet, and operatively coupled to theprocessor.

The pressure monitoring process can detect a drift of a PRV setpointoutlet pressure. The pressure monitoring process can detect a failure oronset of the failure of the PRV. The leak detection system can furtherinclude a pressure control valve controlled by the PRV, the PRV actingas a pilot PRV. The pressure monitoring process can detect a failure oronset of the failure of the pressure control valve.

The leak detection system can further include an isolation valve fluidlycoupled downstream of the PRV.

The isolation valve can include a manually controlled isolation valve.The isolation valve can include an automatic controlled isolation valveoperatively coupled to a processor to periodically close the isolationvalve during times of water system no use or times of no occupancy of ahome or building.

A method to give an indicia of a fixture leak includes: providing apressure regulating valve (PRV) having a PRV inlet and a PRV outlet, thePRV operative during a flow of water through the PRV, and the PRVpressure at a lockup pressure during no water flow through the PRV, anoutlet pressure sensor fluidly coupled to the PRV outlet to measure aPRV outlet pressure, a processor operatively coupled to the outletpressure sensor the processor configured to run a pressure monitoringprocess; and detecting changes in the PRV outlet pressure at the PRVoutlet when the PRV pressure falls below the lockup pressure whileremaining above a setpoint pressure to give an indicia of the a fixtureleak.

The step of providing can further include providing the inlet sensor atthe PRV inlet, and the step of detecting can include detecting changesin the pressure at the PRV outlet and the PRV inlet when the PRVpressure falls below the lockup pressure while remaining above thesetpoint pressure to give an indicia of the a fixture leak. The step ofproviding can further include providing the isolation valve fluidlycoupled downstream of the PRV, and at before the step of detecting canfurther include the step of stopping the flow of water through the PRVto determine a current lockup pressure.

The step of stopping the flow of water can include stopping the flowduring a time of no home or building occupancy, to measure the lockuppressure. The step of stopping the flow of water can includeautomatically closing the isolation valve by the processor during a timeof no home or building occupancy.

The foregoing and other aspects, features, and advantages of theapplication will become more apparent from the following description andfrom the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the application can be better understood with referenceto the drawings described below, and the claims. The drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles described herein. In the drawings, likenumerals are used to indicate like parts throughout the various views.

FIG. 1A is a drawing showing a smart PRV according to the Application;

FIG. 1B is a drawing showing the smart PRV according to the Applicationoperatively coupled to a processor;

FIG. 2 is a graph showing pressure vs. flow for a direct action pressureregulator;

FIG. 3 is a graph showing the outlet pressure change in response to anultra-low flow leak downstream suddenly opening up; and

FIG. 4 is a drawing showing an exemplary ACV

FIG. 5A is a drawing showing a piping and instrumentation diagram (P&ID)of the system according to the Application as shown in FIG. 1A with anadditional isolation valve downstream of the PRV; and

FIG. 5B is a drawing showing a piping and instrumentation diagram (P&ID)of the system according to the Application as shown in FIG. 5A where theisolation valve is controlled by a processor.

DETAILED DESCRIPTION

As described hereinabove, regulating valves (PRV) are used to convert arelatively high pressure supply line to a relatively constant pressureoutlet. One application of a PRV is to convert a relatively highpressure municipal water supply line to a relatively constant lowerwater outlet pressure to the plumbing of a home or building. In higherflow rate applications, such as a large commercial building or facility,the primary pressure regulating element is more likely to be a pilotoperated regulator typically larger than a direct acting regulator. Thelarger pressure control valve is typically pneumatically orhydraulically controlled by a pilot valve. The pilot valve is often adirect acting regulator.

One problem common to plumbed water systems is a water leak,particularly, a relatively low flow water leak. Such leaks are not onlywasteful but might lead to water damage in the vicinity of the leak. Onemethod of the prior art to find a leak includes isolating a home orbuilding from the water source, pressurizing the home or building watersystem, and observing the pressure decay curve to determine if theplumbing system is leaking. While effective at identifying a leakingsystem, the plumbing system is shut off and unavailable during the leaktest, inconveniencing the homeowner or building occupants. That is,according to most methods of the prior art, leaks can only be detectedwhile the water system is turned off.

It was realized that by monitoring the pressure at the outlet of a PRV,or at both of the inlet and outlet, by use of a new pressure monitoringprocess based on the pressure measurements, leaks can be identifiedwithout need to isolate the home or building plumbed system, and withoutinconvenience to the users. Moreover, it was realized that a similarpressure monitoring can be used to both check and monitor the setpointpressure in response to PRV aging. It was also realized that thepressure monitoring can be used to identify a failing PRV valve.Finally, as a PRV can be used as the control element of a much largerpressure control valve, it was realized that the above solutions for astandalone PRV installation can also work by monitoring the same outletpressure (or, preferably both inlet and outlet pressure) of a smart PRVwhich is in service as the control element of a large pressure controlvalve.

Generally, the system and method for leak detection based on PRV outletpressure monitoring according to the Application, detects leaks bydetecting small, sustained flows. Those small, sustained flows reducethe outlet pressure of the PRV to be below the lockup pressure, butstill above the setpoint pressure. Thus, a ‘Smart PRV’ according to theApplication acts as a small-flow detector to find the leaks. Pressurebelow the lockup pressure, but still above the setpoint pressure isimportant for determining the difference between a normal flow and aleak. Normal flow regularly causes deviation from the lockup pressure,however pressures below the lockup pressure, but still above thesetpoint indicate a very small flow that could be a leak.

In typical operation, such as to regulate water pressure to a home orsmall building, a relatively high water pressure line enters the home orbuilding and the PRV lowers the water pressure at the PRV outletconnected to supply the home or building plumbing system to a typicalhome or building operating water pressure. For example, municipal waterpressure lines can vary from about 60 psi to 200 psi, in someresidential neighborhoods typically lower, from about 60 psi to 100 psi.The PRV is typically set to convert the higher supply side pressure toabout 40 psi to 50 psi, for example, for a home water plumbing systemwhich supplies water to the various fixtures and appliances of the home.

The new process is based on the lockup pressure of a direct actingregulator. In the home example described hereinabove, at installation,the PRV is set to, for example, 40 psi. Within some normal precision ofthe PRV, perhaps on the order of plus or minus a couple of psi orbetter, for modest changes in pressure on the supply side and variousoperations of fixtures and appliances in the home, the PRV will maintainits outlet pressure to about 40 psi. During such operation, the PRVvalve is said to be operating within a best operating range.

The new process is based on the lockup pressure of a direct actingregulator. When there is normal high pressure on the supply side of thePRV, such as, when no person and no appliances are using water in thehome, there is a no flow situation. In a no flow situation, the waterpressure at the outlet side of the direct acting regulator rises,typically by about 2% to 10% over the predetermined setpoint, thedesired home pressure, 40 psi continuing the above example. In the PRVlockup mode, the outlet pressure might rise to about 41 psi.Particularly in a home, or small building, there are likely to beperiods of times when there are no-flow situations (no demand), such asin the overnight hours.

One exemplary smart PRV system to carry out the new process is a leakdetection system for a building which includes a pressure regulatingvalve (PRV) having a PRV inlet and a PRV outlet. The PRV can be normallyoperative in a best operating range mode and a in a lockup mode duringtime periods of no flow. An outlet pressure sensor is in fluidcommunication with the PRV outlet to measure the PRV outlet pressure. Aprocessor is operatively coupled to the outlet pressure sensor. Theprocessor runs a pressure monitoring process to detect changes in thePRV outlet pressure when the PRV is in the lockup mode to give indiciaof a building leak condition. (See for example, FIG. 1A where itunderstood that any pressure (or temperature sensors) present, at theinlet and/or outlet are operatively coupled to a processor by anysuitable wired or wireless connection. The processor running thepressure monitoring process can be disposed on, at, or near the PRV, orthere can be any suitable wired or wireless connection (e.g., Internet,cellular, etc.) to a remote computer that runs the pressure monitoringprocess. FIG. 1B is a drawing showing the smart PRV according to theApplication operatively coupled to a processor 191. Processor 191 isoperatively coupled to memory 193.

By monitoring pressure over time by a pressure monitoring processrunning on any suitable processor, such as, for example, a relativelysimple controller or process controller, the pressure monitoring processcan look for certain patterns of changes in the pressure, particularlyduring times of no flow when the PRV is in the lockup mode. For example,if the lockup pressure is about 41 psi, and the pressure monitoringprocess records a relatively steep change (large slope) change in theoutlet pressure from the previous no flow lock up condition, such achange is likely indicative of a water leak in the plumbing system ofthe building. Such a leak can be a leak in the pipes, a fixture leak, oran appliance leak. Thus, a new type of leak detection system and methodbased on monitoring pressure changes in the outlet pressure of a PRV atno flow (or constant very low flow) where the PRV is in the lock upcondition, outside of the normal best operating range.

As a test, we simulated a relatively tiny leak of less than 10 mL/hour,and found that when the leak began, we could detect it at the PRV outletby observing a detectable pressure change, for example, from about 41.1psi to about 40.2 psi on the order of one second. Moreover, for therelatively fast leak onset over a second, there was also detected arecover curve on the order of 10 to 20 seconds which contains additionalinformation about a leak, such as rate of onset of the leak. (See forexample, FIG. 2)

Based on a known or measured relationship between inlet pressure andlockup pressure, there is additional information which can be determinedfrom the lockup pressure, such as inferred changes in inlet pressure.However, by adding a second inlet pressure sensor, changes in lockuppressure can be more directly determined to be caused by changes in theinlet pressure, or a change on the outlet building side of the PRV.

Especially where both inlet and outlet pressure are monitored by thepressure monitoring process over time, there can also be informationdetermined about any change in the PRV setpoint pressure, such as, forexample as caused by valve aging. Moreover, by observation of changes ofboth inlet pressure and outlet pressure, there can be observations ofthe health of the PRV itself, such as for example a determination of PRVfailure, such as can be caused by failure of internal parts including adrying out or stiffening of pliable valve or seating elements.

It was also realized that the same pressure monitoring smart PRV systemand process can similarly measure either just the outlet pressure, orpreferably both the inlet and outlet pressure of a PRV installed as apilot PRV of a much larger pressure control valve. Here, while theactual pressure measurements are made as before at the PRV, it turns outthat the same determinations can be made as to leak detection, setpointdrift, and the health of the larger pressure control valve which isbeing controlled by the pilot PRV, such as changes in the buildingplumbing system, condition and setpoint of the PRV, and condition of thelarger pressure control valve.

Another problem is that some buildings may already have a leak when thisleak detecting device is installed.

In this case, a solution is to add an isolation valve, downstream of thePRV (typically immediately downstream), to determine the true lockuppressure of the PRV by ensuring that there is no flow through the PRV.The isolation valve can be manual or automatic (e.g. motor controlled byany suitable processor based controller). A manual isolation valve canbe used during an installation procedure to set the lockup pressure. Anautomatic isolation valve can briefly shut off flow through the PRV attimes, such as, when no one in the building is using water. Thisautomatic feature enables the processor to track any drift in lockuppressure, increasing the accuracy of the leak detection algorithm, andmonitoring the health of the PRV, by updating the lockup pressure. Anincrease in lockup pressure can also indicate a stiffening of the rubbersealing disc or damage to the seat of the PRV (or, an ACV as describedherein below, where controlled by a PRV.

Note that, a leak is not detected while the isolation valve is closedbecause as long as the isolation valve is closed, the valve will be inlockup. However, the isolation valve closed state does allow the systemto intelligently update the lockup pressure of the valve, which canchange over time. This update of the update the lockup pressure of thevalve increases the sensitivity and accuracy of the system. After thelockup pressure is re-evaluated and the isolation valve is opened, thesystem and method can then return to detecting leaks by monitoring forpressures below the lockup pressure, but still above the setpoint of thePRV.

FIG. 5A is a drawing showing a piping and instrumentation diagram (P&ID)of the system according to the Application as shown in FIG. 1 with anadditional isolation valve 500 downstream of the PRV 100. The isolationvalve 500 downstream of the PRV can be used to force the PRV 100 tolockup.

FIG. 5B is a drawing showing a piping and instrumentation diagram (P&ID)of the system according to the Application as shown in FIG. 5A where theisolation valve is controlled by a processor. As described hereinabove,valve 501 of the isolation valve 500 can be either a manual valve, or asshown in FIG. 5A include a motor 503 for automatic operation ascontrolled by a processor 191, such as a processor of a processor basedcontroller.

The pressure monitoring process can consider, for example, magnitude ofpressure changes, slope in time of pressure changes, and shapes ofpressure change curves, including decay or oscillation curves.

Example— FIG. 1 is a drawing showing a smart PRV according to theApplication. T&P denote temperature and pressure sensors, the pressuresensors most relevant to this application. FIG. 2 is a graph showingpressure vs. flow for a direct action pressure regulator. FIG. 3 is agraph showing the outlet pressure change in response to an ultra-lowflow leak downstream suddenly opening up.

Pressure regulating valve (PRV) 100 has two pressure sensors, inletvalve pressure sensor 140 connected to the valve inlet, and outlet valvepressure sensor 160 connected to the valve outlet as shown in FIG. 1. Asshown in FIG. 2, the outlet valve pressure sensor 160 monitors the setpressure 210, lockup pressure 220, and falloff pressure 230 of the PRV100. Because these phenomena are influenced by the inlet pressure, theinlet valve pressure sensor 140 can be used to monitor the upstreampressure. By using both sensors together, it is possible to separate theeffect of upstream and downstream events on the valve outlet. Bytracking the behavior of the valve over time, it is possible to separateout the effect of slow shifts in the mechanisms and materials from moresudden changes in downstream plumbing systems.

Flow can be estimated using a response surface generated in a lab ormanufacturing facility. Because the response surface is very sensitiveat low flows, due to the phenomenon of lockup, the new system and methodof the Application is particularly effective at detecting leaks withoutthe need for a flow sensor or an isolation valve to watch for pressuredecay. That flow information can be used to provide insights to thebuilding owner and operator about water usage and the health of theirplumbing system. Drift in the performance of the PRV can be identifiedby tracking the lockup and setpoint pressures over time. If significantdrift occurs, the smart valve system can notify the building owner of avalve malfunction that is exposing their plumbing system to excessivelyhigh pressures. Tracking drift also lets the valve monitoring algorithmseparate slow changes in the operation of the valve from more suddendownstream leaks. The setpoint of the valve can be automaticallydetermined during installation of the valve.

An Automatic Control Valve (ACV) is a regulator valve with fluid in thetop of the valve instead of the spring in a PRV. Plumbing, or pilotrycan be used to control the flow of fluid into and out of the top of thevalve, actuating the membrane and orifice, thereby controlling theoperation of the valve. When a PRV is the pilot for an ACV, the ACVregulates the outlet pressure to the set pressure of the PRV. By usingthe smart PRV described hereinabove, the ACV will have the same flowqualifying ability.

Example— FIG. 4 is a drawing showing an exemplary ACV suitable for useas described hereinabove. The exemplary ACV is a 5115 pressure reducingcontrol valve available from the Watts Corporation of North Andover,Mass.

Processor—Any suitable processor can be used to run the pressuremonitoring process. Suitable processors include controllers,programmable logic controllers, microcomputers, computers, computerservers, etc.

Software, programming code, firmware, etc. to implement a pressuremonitoring process as described hereinabove can be provided on acomputer readable non-transitory storage medium. A computer readablenon-transitory storage medium as non-transitory data storage includesany data stored on any suitable media in a non-fleeting manner Such datastorage includes any suitable computer readable non-transitory storagemedium, including, but not limited to hard drives, non-volatile RAM, SSDdevices, CDs, DVDs, etc.

It will be appreciated that variants of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be combined intomany other different systems or applications. Various presentlyunforeseen or unanticipated alternatives, modifications, variations, orimprovements therein may be subsequently made by those skilled in theart which are also intended to be encompassed by the following claims.

What is claimed is:
 1. A leak detection system for a buildingcomprising: a pressure regulating valve (PRV) having a PRV inlet and aPRV outlet, said PRV operative during a flow of water through said PRV,and a PRV pressure at a lockup pressure during no water flow throughsaid PRV; an outlet pressure sensor fluidly coupled to said PRV outletto measure a PRV outlet pressure; and a processor operatively coupled tosaid outlet pressure sensor; said processor configured to run a pressuremonitoring process to detect changes in pressure at said PRV outlet whensaid PRV pressure falls below said lockup pressure while remaining abovea setpoint pressure to give an indicia of a fixture leak.
 2. The leakdetection system of claim 1, further comprising an inlet pressure sensorfluidly coupled to said PRV inlet, and operatively coupled to saidprocessor.
 3. The leak detection system of claim 2, wherein saidpressure monitoring process to detect a drift of a PRV setpoint outletpressure.
 4. The leak detection system of claim 2, wherein said pressuremonitoring process to detect a failure or onset of said failure of saidPRV.
 5. The leak detection system of claim 1, further comprising apressure control valve controlled by said PRV, said PRV acting as apilot PRV.
 6. The leak detection system of claim 5, wherein saidpressure monitoring process to detect a failure or onset of said failureof said pressure control valve.
 7. The leak detection system of claim 1,further comprising an isolation valve fluidly coupled downstream of saidPRV.
 8. The leak detection system of claim 7, wherein said isolationvalve comprises a manually controlled isolation valve.
 9. The leakdetection system of claim 7, wherein said isolation valve comprises anautomatic controlled isolation valve operatively coupled to a processorto periodically close said isolation valve during times of water systemno use or times of no occupancy of a home or building.
 10. A method togive an indicia of a fixture leak comprising: providing a pressureregulating valve (PRV) having a PRV inlet and a PRV outlet, said PRVoperative during a flow of water through said PRV, and said PRV pressureat a lockup pressure during no water flow through said PRV, an outletpressure sensor fluidly coupled to said PRV outlet to measure a PRVoutlet pressure, a processor operatively coupled to said outlet pressuresensor said processor configured to run a pressure monitoring process;and detecting changes in said PRV outlet pressure at said PRV outletwhen said PRV pressure falls below said lockup pressure while remainingabove a setpoint pressure to give an indicia of the a fixture leak. 11.The method of claim 10, wherein said step of providing further includesproviding said inlet sensor at said PRV inlet, and said step ofdetecting comprises detecting changes in said pressure at said PRVoutlet and said PRV inlet when said PRV pressure falls below said lockuppressure while remaining above said setpoint pressure to give an indiciaof said a fixture leak.
 12. The method of claim 10, wherein said step ofproviding further includes providing said isolation valve fluidlycoupled downstream of said PRV, and before said step of detectingfurther comprises said step of stopping said flow of water through saidPRV to determine a current lockup pressure.
 13. The method of claim 12,wherein said step of stopping said flow of water comprises stopping saidflow during a time of no home or building occupancy, to measure saidlockup pressure.
 14. The method of claim 12, wherein said step ofstopping said flow of water comprises automatically closing saidisolation valve by said processor during a time of no home or buildingoccupancy.